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Unformatted text preview: id = ‐911 J exothermic Work occurs as the sample expands or contracts. Overall: ΔE = q + w Conservation of Energy and Changes of State
A system does 50.2 J of work on its surroundings and there is a simultaneous 90.1 J heat transfer from the surroundings to the system. What is ΔEsystem?
Work done on the surroundings by the system
Heat transfers from the surroundings to the system
wsystem = ‐50.2 J qsystem = (qsurroundings = +911 J)
ΔEsystem = qsystem + wsystem ΔEliquid = ‐911J ΔEsystem = ‐50.2 J +90.1 J = +39.9 J Enthalpy: Heat Transfer at Constant P During freezing (or melting)
ΔE = qV • subscript V shows fixed V
• work requires...
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- Spring '07
- States Of Matter